10 yards isn't nearly enough for any commercial
vessel. I understand close quarters will occur in racing
but there's absolutely no reason to get that close, at that distance you've already caused a lot of worry.
I agree that 10 yards is too close if it's off the bow or on a collision
course from either of the forward quarters. But if you're going west and not towing, and I am going north or south, sailing up to within 10 yards of your stern isn't going to cause a problem, and shouldn't cause you any worry.
One day about 35 years ago I was sailing east under the Golden Gate Bridge. The breeze was light and I was going about 3 knots in a Catalina
22, just lolling around in the sun. I should have been watching my stern more carefully, but I wasn't. I was laying down in the cockpit
and watching to the side and over the stern every few minutes, like 3. But my head
was not high and it wasn't very far until my line of sight was very high off the water
. About due north of Anita Rock I noticed a grey wall about 15 yards to my portand when I looked up I could see a few sailors looking down at me. As the ship got beam to beam with me it was only about 5 yards away. I braced for an expected prop wash, but there was none. No noise
either, not even a horn. Since it was obvious that his crew saw me and I did not get 5 horn blasts I guess that the skipper
of the freighter was sure that he would clear me.